Leishmaniasis in a dog native to Colorado

Area of Science:

• Veterinary Medicine
• Infectious Diseases
• Parasitology

Background:

• Leishmaniasis is a parasitic disease caused by Leishmania species.
• Infections in dogs can lead to severe dermatologic and systemic manifestations.
• Geographic distribution of Leishmania is expanding, posing a risk in new regions.

Purpose of the Study:

• To report a case of canine leishmaniasis in a dog presenting with dermatologic lesions, weight loss, and diarrhea.
• To detail the diagnostic methods used to confirm Leishmania infection.
• To discuss the potential for endemic spread and clinical relevance in dogs.

Main Methods:

• Clinical evaluation of a 1-year-old foxhound-Treeing Walker Coonhound cross with a history of skin lesions, weight loss, and diarrhea.
• Diagnostic workup including physical examination, hematology, serum biochemistry, urinalysis, abdominal ultrasonography, ELISA, indirect fluorescent antibody test, PCR, and skin biopsy.
• Histopathologic examination for Leishmania amastigotes.

Main Results:

• The dog exhibited muscle wasting, lymphadenopathy, pruritic dermatologic lesions, anemia, monocytosis, hypercalcemia, hyperproteinemia, hyperglobulinemia, and proteinuria.
• Diagnosis of leishmaniasis was confirmed by positive ELISA, high indirect fluorescent antibody titer (1:1,024) for Leishmania infantum, positive PCR for Leishmania DNA in blood and lymph node aspirate, and identification of amastigotes in skin.
• The dog had a low CD4+:CD8+ lymphocyte ratio (1:1) and was euthanized due to disease severity. The dam and a littermate also had high antibody titers, suggesting potential vertical transmission or endemicity.

Conclusions:

• Leishmaniasis should be considered in the differential diagnosis for dogs presenting with scaly dermatoses.
• The case suggests that Leishmania infantum may be endemic in Colorado.
• Potential vertical transmission was suspected, emphasizing the importance of monitoring breeding lines.